What is American skunk cabbage?

American skunk cabbage is an invasive non-native plant that originates from Western North America which was introduced to the UK as an ornamental plant in 1901. The plant was first recorded in the wild in 1947 and has since then spread across Britain, particularly in southern and western areas.

How do you identify American skunk-cabbage?

It’s certainly a showy plant – American skunk-cabbage can grow up to 1.5m in height, with a basal rosette of impressive leathery green leaves that grow up to about 70cm long.

If you don’t see it, you’ll definitely smell it! American skunk-cabbage emits a strong odour, like that of a skunk, from bright yellow flowers that emerge before the leaves in spring and that are reminiscent of lords-and-ladies.

Its normal habitat is wet woodland, as American skunk-cabbage needs a wet site to grow, although it has no specific soil requirements – it can occur in soils from light sand to heavy clay that are acid, neutral or alkaline.

What’s the issue with American skunk-cabbage?

The large leaves and dense stands of the plant lead to it out-competing smaller plants due to its shading effect and can cause serious damage locally to native flora. It can grow in shade or full-light and in a range of different soil conditions and thrives in disturbed environments. 

Skunk-cabbage spreads from both its underground rhizome roots and from seed production. A large seed bank can build up in the soil and can remain viable for around 8-9 years! Seeds may be dispersed via waterways but also probably by birds and mammals.

On sale as recently as 2009, this invasive non-native plant is relatively new to the recognised group, so it’s likely we will see further introductions into the wild and increased problems.

How do we manage American skunk cabbage on our reserves?

On the plus side the plant is slow growing and doesn’t produce flowers for the first few years.

It’s important to find the source of this plant to stop the spread, so following the plants or watercourse and working with neighbours and landowners to get it removed from their land upstream is very important.
We usually dig the plant out, including the underground rhizome. All the plant matter is collected, so that a fragment of rhizome doesn’t regrow. The debris can then be burnt, dried out (away from watercourses) or securely composted.

Sometimes it is too wet and dangerous to dig, or the plant may be growing from rocky ground. In this case, a herbicide treatment could be used. The problem is that the plant is likely to be on or close to a water body or watercourse, so the herbicide would need to be applied by a licenced person and consent sought from the Environment Agency prior to any application.

If you discover this species in your garden, a quick thing you can do is chop off the flower spike to stop it seeding. This will give you chance to remove the seed spread whilst you deal with the plant itself.